Break up e2e Error UI tests and fix flakiness

[chrisbreiding]

• Closes Flaky internal test: Timeout of 180000ms exceeded in 8_error_ui_spec #7671

User facing changelog

N/A - Internal only

Additional details

• Breaks up the e2e tests into multiple files so they don't take too long and time out.
• Fixes an issue where one of the tests plus firefox garbage collection caused a failure.
• Adds better error output, so if a test do fail, it's easier to find which one it is.

[cypress-bot]

Thanks for taking the time to open a PR!

• Create a Draft Pull Request if your PR is not ready for review. Mark the PR as Ready for Review when you're ready for a Cypress team member to review the PR.
• Become familiar with the Code Review Checklist for guidelines on coding standards and what needs to be done before a PR can be merged.

[cypress]

---

Test summary

7652 • 0 • 119 • 0

---

Run details

Project	cypress
Status	Passed
Commit	188bbce
Started	Jun 19, 2020 1:17 PM
Ended	Jun 19, 2020 1:24 PM
Duration	07:02 💡
OS	Linux Debian - 10.1
Browser	Multiple

View run in Cypress Dashboard ➡️

---

This comment has been generated by cypress-bot as a result of this project's GitHub integration settings. You can manage this integration in this project's settings in the Cypress Dashboard

[chrisbreiding]

Looks like the timeouts were hiding some legitimate failures/flakiness. If I have time, I'll look into fixing them. Or if the isolated runner PR gets in first, will just move these tests to that.

[brian-mann]

The isolated runner PR has been in for about a week now - get with @bkucera on transferring these over.

[chrisbreiding]

I experimented with moving them to the isolated runner. Unfortunately, it doesn't look like it will work for these tests as it currently stands. Since it evals the test function, the errors don't end up with a stack trace. It might be possible to get it to work with some updates to the isolated runner.

In any case, it would be valuable to merge the changes in this PR now as they are, since the flakiness of these tests are slowing down other PRs. I can take another look at moving them to the isolated runner next week.

[jennifer-shehane]

It'd be a bit nicer if the sets of tests had some kind of logical grouping instead of 1, 2, 3 - it's a bit unclear if I needed to add a new test where to put it. But, this should be an improvement overall. 👍

sorry, have some more things to say

[jennifer-shehane]

There are a couple of failures in the 8_errors_ui now after these changes. And...they're a bit confusing to debug I think. Maybe I don't understand the structure well enough. The message is below.

1. So, what was the actual state of this test? Did it pass when it was supposed to fail or did it fail when it was supposed to pass?
2. Is there any way to print which test file failed? It'd be a lot quicker to debug if I could jump straight to the file? Right now I look up onResponse assertion failure and there are 4 matches, so then I have to track down which file/line this one was.

[chrisbreiding]

Closing in favor of #7831